(a) Field of the Invention
The present invention relates to a process for preparing polyurethane particulate and polyurethane particulate prepared therefrom, and more particularly to a process for preparing polyurethane particulate and spherical polyurethane particulate prepared therefrom that is capable of having thermoplastic and thermosetting properties, having uniform and regular form, and that is economical due to a simple manufacture process by using an inorganic stabilizer as a suspension stabilizer in the manufacture process of the polyurethane particulate.
(b) Description of the Related Art
The polyurethane particulate has been used as an additive for paints, as an additive for print-ink, as a resin modifying agent, for cosmetics, for an interior material or bumper material for automobile use, and the like.
In order to prepare the polyurethane particulate, the related art has used a method for mechanically grinding polyurethane in a solid state at a low temperature, and a method for extracting and drying polyurethane from a water-dispersion in which polyurethane is dispersed in water.
U.S. Pat. No. 3,787,525 discloses the method for preparing polyurethane particulate by using an inert solvent with polyurethane prepared through solution-polymerization.
Japan Patent Application Publication 2004-107476 discloses a method for preparing polyurethane beads by dispersing an isocyanate prepolymer in water using an organic suspension stabilizer such as a cellulose aqueous resin, a polyvinyl alcohol, polyvinyl pyrrolidone, and the like, and heating them.
Japan Patent Application Publication 1999-116649 discloses a method for preparing spherical particles by contacting a dispersion media and a polyurethane prepolymer solution by a rigid porous film having a uniform pore diameter, extruding by adding pressure into the dispersion media state, and curing the resultant, so as to prepare monodisperse polyurethane beads.
However, the polyurethane particles obtained by the method of the related art tends to result in amorphous form rather than spherical form. Also, it has problems that particles with desired-size cannot be formed, the manufacturing cost is high, and the process is complicated.
Also, the organic suspension stabilizer used in the particle preparation can result in impurities, and thus a washing process needs to be performed in the preparation procedure. Furthermore, when the organic suspension stabilizer is used, the washing condition is complicated and the pigment and the stabilizer can be removed during the washing process.
SUMMARY OF THE INVENTION
Thus, in order to resolve the above problems of the related arts, in a process for preparing a polyurethane particulate using a compound having at least one isocyanate group and a compound having at least one active hydrogen in the presence of a suspension stabilizer, the present invention is perfected by confirming that almost no foam is generated in a washing process by using an inorganic metal compound as the suspension stabilizer compared with an organic suspension stabilizer, and each of a thermoplastic and a thermosetting polyurethane particulate having superior properties can be prepared according to the number of functional groups of the compound having at least one isocyanate group and the compound having at least one active hydrogen.
Therefore, it is an object of the present invention to provide a process for preparing a polyurethane particulate that is easy to wash, in which it is easy to control particle size and form, and in which a uniform and regular size distribution of a desired particulate size can be obtained.
Another object of the present invention is to provide a polyurethane particulate that is able to be used with special quality of the thermoplastic and thermosetting polyurethane, and that stably exhibits a color.